| Spinetoram is a kind of natural substance produced by soil actinomycete, which is toxic to many major agricultural insect pests. At present, spinetoram becomes a potential insecticide to control insect pests in the market because of its novel special action mechanism. Spinetoram is effective to some lepidoptera species, such as cotton bollworm, Helicoverpa armigera (Hubner), and research on the action mechanism of spinetoram on H. armigera could provide a theoretical basis for rational use of spinetoram. The main results are as follow:1. Both spinetoram and abamectin had lethal effect to some lepidoptera species such as H. armigera, Spodoptera exigura, Spodoptera litura and Agrotis ipsilon. Compared with abamectin, spinetoram had better control efficiency to these four lepidoptera species, but spinetoram had no activity on Apolygus lucorum and Aphis gossypii, while abamectin could control A. gossypii well. The toxic efficiency of spinetoram and abamectin to H. armigera which collected from different geographical locations were determinated. Spinetoram had better efficiency than abamectin, and the differences of LC50S of spinetoram among H. armigera populations from different locations were not significant, but differences of the LC50S of abamectin among different location populations were obvious. After treated Bt-resistant and Bt-susceptible H. armigera strain with spinetoram, the results showed a little negative cross-resistance between spinetoram and Bt.2. The impact of spinetoram on major insect pests and natural enemies in cotton field were evaluated by field plot experiments. Compared with control, high-dose of spinetoram and abamectin could inhibit the population increase of cotton aphid and cotton mirid bug, but had no obviously effect on whitefly population. Spinetoram had no obviously effect on parasitoids and predators such as ladybug, orius, and lacewing.3. The effects of sub-lethal dose of spinetoram on growth and development of H. armigera were analyzed. After treated by spinetoram, the survival percentage of H. armigera larvea reduced along with increasing of the treated dose. The larval weight, pupal weight, pupation rate and eclosion rate reduced after treated by spinetoram at different doses. The larval development time, pre-pupal duration and pupal duration delayed, the eggs laid per female and egg hatch percentage were also reduced after treated with spinetoram.4. The enzyme activities of H. armigera larvae were changed after treated withdifferent dose of spinetoram. The activities of CarE (carboxylesterase) and GST (glutathione-S-transferases) were reduced along with increasing of the treated doses. However, the activities of AchE (acetylcholinesterase) and MFO (mixed-function oxidases) were promoted along with increasing of the treated doses.5. The gene changes of H. armigera larvae aftertreated with spinetoram were analyzed at transcriptional level using transcriptome sequencing analysis method, and expressions of parts of changed genes were verified by qRT-PCR. By transcriptome and bio-information analysis, we found some genes expressed higher and some expressed lower in treated H. armigera larvae than control. The unigenes maybe involved in the action process of spinetoram on H. armigera, and the functions of these unigenes were annotated as action target, cutieular protein, detoxification and metabolism, repair and immune, and regulation. |
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